The invention relates to a cleaning tablet for the automatic cleaning of dentures in an aqueous solution having a content of sodium hydrogen carbonate and/or sodium carbonate or carbonates, citric acid or citrate or citrates, sodium perborate, potassium monopersulphate, surfactants and foam forming agents, binders, lubricants and disintegrants, antimicrobial agents, carriers, flavoring/aromatizing substances, at least one perborate/peroxide activator and at least one phosphorous compound.
Denture cleaning tablets, for example of the type described in DE-OS 21 33 710, are used in such a way that they are placed in water at the same time as the denture to be cleaned. When so placed in water the cleaning tablet disintegrates with a more or less pronounced evolution of gas and releases active substances, which attack and remove the contaminant coatings adhering to the denture.
Such cleaning tablets, such as those forming the subject matter of German patent Nos. 23 12 847, 25 48 469, 26 58 450 and 27 41 072, European patent Nos. 0010 412, 0 028 005 and 0 102 418, as well as EP-OS Nos. 0 133 354, 0 149 308, 0 157 464 and 0 225 658, essentially contain oxygen-delivering substances for oxidizing and disinfecting (such as monopersulphates and/or perborates), inorganic softeners and lime binding agents (such as phosphates and/or polyphosphates), chelating agents, such as EDTA, gas-forming carriers, such as carbonates and/or bicarbonates, citric acid, tartaric acid, amidosulphonic acid or their salts, disinfectants, such as benzoates and/or alkyl hydroxybenzoates, as well as lubricants, binders and/or disintegrants, surfactants, colourants and finally flavouring/aromatizing agents. As a function of the composition, when they dissolve in water the pH-values fluctuate between acid, neutral and alkaline. These tablets are generally rapid cleaning tablets; having a cleaning time of 10 to 15 minutes. However, in certain cases they are slow acting tablets having relatively long use periods, in which the full cleaning action with respect to the denture being treated therein is only achieved after roughly 1 to 2 hours.
With respect to the cleaning of dentures, all the aforementioned tablets suffer a disadvantage which is typical for the composition and use practice. The formation of the perborate oxygen in the desired active form via the HOO-ion only takes place in a satisfactory manner at temperatures above 60.degree. C. However, generally dentures are cleaned by the user in 10 to 15 minutes at roughly 30.degree. to 40.degree. C., so that in the case of the known cleaning tablets a considerable part of the intended oxidizing and disinfecting action of the oxygen-delivering substances is not brought about.
EP-OS No. 0 253 772 discloses a cleaning tablet of the aforementioned type, in which the phosphorus compound is constituted by a phosphate combination, which assists or participates in the cleaning process, whilst polymeric fluorocarbon is used as the binder. When using such a hydrophobic fluorocarbon, however, presents a problem. Due to the hydrophobic nature of the cleaning tablet not only is dissolving the tablet made more difficult, but also it floats in the dissolved cleaning liquid in a reactant-separating manner and therefore delays the cleaning action. The use of such a polymeric, hydrophobic binder demonstrates why in the case of the cleaning tablet of EP-OS No. 0 253 772, a high activator content of 5 to 15% by weight is used, which leads to a loss of content of the actual cleaning-specific, active substances. As stated, in the known cleaning tablet, use is also made of inorganic phosphates, which in the same way as the EDTA used act as a metal bonding agent, but are not unobjectionable due to possible environmental influences.